引蛇出洞 means tempting a hidden target out into the open so it can be caught. Compare 调虎离山 ('lure the tiger away from the mountain'), one of the 三十六计, which draws an opponent away from a strong position rather than out of hiding.
usage
Neutral in everyday use: police stings, sales tactics, tests that coax a fault into showing itself. It always implies a deliberate trap, so it never describes an honest invitation.
